void main() {
  // 运算符
  double num = 15;
  int number = 10;
  double result = num * number;

  double num1 = 10;
  double num2 = 16;
  double num3 = 21;
  double result2 = num1 + num2 + num3;
  print('$result $result2');
  double num4 = num / 6;
  print(num4);



 int n1 = 10;
 n1 += 1;
 n1 *= 2;
 n1 ++;

  //fultter没有===
  int a1 = 5;
  int a2 = 5; 
  int a3 = 8;
  a1 == a2;
  a1 >= a2;
  a1 > a3;
  a1 != a3;

  // 逻辑与或非
  int age =15;
  int years = 50;
  bool result3 = age > 18 && years > 30;
  bool result4 = age > 18 || years > 30;
  bool result5 = !result3;
  print('$result3 $result4 $result5');
}